The invention relates to a fluid power arrangement comprising a valve means and a fluid power implement, which is connected or is able to be connected with the valve means by way of a first fluid line and at least one second fluid line for fluid actuation through the valve means, the valve means and the implement constituting spatially separate assembly units, the valve means having a first valve fluid port for the first fluid line and at least one second valve fluid port for the at least one second fluid line and the implement having a first implement fluid port for the first fluid line and at least one second implement fluid port for the at least one second fluid line.
The implement may for example be a pneumatic cylinder, which is pneumatically controlled using the valve means, as for example a servo valve. Prior to putting the two assembly units into operation they must be joined together by way of fluid line, as a rule flexible hose. Here errors may occur so that for example the first valve fluid port is misjoined to the second implement fluid port and the second valve fluid port is misjoined with the first implement fluid port. Accordingly as a rule a functional test is performed, that is to say, the arrangement is subjected to a low working pressure so that any possible erroneous hose placement cannot lead to damage to the fluid power arrangement owing to slow speeds and low force levels.
Such a test is however time consuming and for many applications it is not practicable. For instance regulated pneumatic implements such as positioning drives, are only put into operation after the overall installation of plant or machinery, as f. i. a machine tool. Then operations are already performed with the normal working pressure, because a regulating means provided for the implement and as a rule controlling the valve means restricts, during regular operation of the plant or machine, speeds, pressures and forces so that damage is precluded. Setting the working pressure to a lower level for testing is frequently impossible, since there are no suitable chokes in the case of regulated implements.
For putting into operation and in particular for a test as to whether hose placement is correct, suitable software may be employed to perform a test run. However there is not always such software available, or the possible user does not employ it owing to ignorance or lack of time.
If now there is an incorrect hose placement or, respectively, an incorrect fluid connection between the valve means and the implement, this may in the worst case entail damage to the fluid power arrangement and/or the plant or machine, which is driven by the fluid power arrangement. There will namely be a parasitic coupling or amplification effect, because the regulator is actually attempting to employ the action of opposite pressure to avoid an actuator member of the implement, as for example its piston, being moved oppositely to the desired or set target direction of motion. Owing to the wrong fluid port between the valve means and the implement this however will entail the opposite effect, that is to say the actuator member subjected to fluid, as for example compressed air, acting oppositely to the desired direction of shifting.
In the case of regulated drives the valve means are furthermore as a rule switching valves. In the case of the implement being in the vicinity of the terminal positions, there are no limit shock absorbers since this function is performed by the regulating means. When the valve means and the implement are incorrectly joined up, an actuator member for example will impact at full charge against the terminal abutment.
Wrong hose placement on the valve means and the implement therefore entails improper functioning, damage and in any case to a delay in putting the system into operation, even if the damage may be avoided by testing.